Heat the oven to 375°F. Line a 9x13-inch baking pan with parchment, letting it overhang two sides for easy lifting.
In a small bowl, whisk together the melted butter, Dijon, honey, Worcestershire, poppy seeds, onion powder, and black pepper. Set aside 2 tablespoons of the glaze for finishing.
Without separating the rolls, slice the entire slab horizontally with a serrated knife to create a top and bottom. Optional for crisper bottoms: place the bottom slab, cut-side up, on the pan and toast in the oven for 3 minutes.
Set the bottom slab in the lined pan and brush lightly with some glaze. Layer on 4 slices of Swiss, shingle the ham evenly over the cheese, then top with the remaining 4 slices of Swiss. Cap with the top slab of rolls.
Brush most of the remaining glaze over the tops and down the sides. Let the sliders stand for 10 minutes so the glaze can soak in while the oven finishes heating.
Cover the pan loosely with foil (tent so it doesn’t touch the rolls) and bake for 15 minutes. Uncover, brush with the reserved glaze, and bake 6–8 minutes more, until tops are deeply golden and the cheese is fully melted.
Cool 5 minutes. Lift the slab out using the parchment, then slice into 12 sliders with a serrated knife. Serve warm.